Bladed rotor



June 27, 1967 R. v. BLACKHURST ETAL 3,327,995

- BLADED ao'ron I Filed July 7, 1966 2 Sheets-Sheet l J1me 1957 R. v. BLACKHURST ETAL BLADED ROTOR 2 Sheets-Sheet 2 Filed July 7, 1966 y 4 a? Attorneys United States Patent 3,327,995 BLADED ROTOR Robert Vaughan Blackhurst, Ripley, and William Harrison, Spondon, England, assignors to Rolls-Royce Limited, Derby, England, a British company Filed July '7, 1966, Ser. No. 563,558 Claims priority, application Great Britain, July 31, 1965, 32,861/ 65 10 Claims. (Cl. 253-77) ABSTRACT OF THE DISCLGSURE A rotor for the compressor or turbine of a gas turbine engine, the rotor having a plurality of blades extending from its periphery, each of the blades having at least one clapper member projecting towards the clapper member of an adjacent blade, and a sleeve-like connecting member extending around the ends of adjacent clapper members. A backing piece may be inserted between the ends of adjacent clapper members, the backing piece being within the sleeve-like connecting member.

The present invention relates to a compressor or turbine rotor for a gas turbine engine having blades with lateral supports and having means to interconnect the lateral supports to impart greater lateral stiffness to the blades.

The lateral supports above-mentioned comprise members projecting from the blade surfaces adapted to extend into the spaces between two adjacent blades. Such lateral supports will hereinafter be referred to as clappers or clapper members.

According to one aspect of the present invention a compressor or turbine rotor for a gas turbine engine comprises a rotor member having a plurality of aerofoil shaped blades mounted on the periphery thereof, each blade having at least one clapper projecting from each of the areofoil surfaces thereof towards the clapper of the next adjacent blade, means being provided for securing the ends of the adjacent clappers of two adjacent blades together in at least each alternate space between the blades.

A strap or sleeve may be used to secure the adjacent ends of the clappers of two adjacent blades.

In a preferred embodiment the strap, sleeve may be made from a fiber reinforced plastic material or alternatively from a fiber reinforced thermosetting resin material.

Preferably a packing piece is inserted between the adjacent ends of the clappers of said pair of clappers.

Also preferably alternate pairs of clappers are interconnected by a strap or sleeve in the above manner.

One embodiment of the invention will now be described in more detail, merely by way of example, with reference to the accompanying drawings in which:

FIGURE 1 illustrates a gas turbine engine having clappered blades according to the present invention,

FIGURE 2 is a view on the line 22 of FIGURE 1,

FIGURE 3 is an enlarged pictorial view of two of the blades of FIGURE 2 showing the assembled blades and clappers of the present invention,

FIGURE 4 is a part sectional view of one of the blades of FIGURE 3,

FIGURE 5 is a sectional side elevation of a further embodiment of the present invention, and

FIGURE 6 is a sectional side elevation of still a further embodiment of the present invention.

Referring now to the drawings in FIGURE 1 there is illustrated a gas turbine engine having compressor means 1, combustion equipment 2, turbine means 3 and a propulsion nozzle 4 all in flow series.

The compressor means 1 comprises a plurality of stages Patented June 27, 1967 of blading each stage consisting of rotors and stators. Due to the length of blades of the first few stages of blading it is necessary to provide lateral support for the rotor baldes to increase their stiffness. Consequently the blades 5 mounted on a rotor disc member 5a of at least the first stage rotor are provided with clappers or clapper members 6 which extend laterally from both of the working surfaces of the blades spanning the spaces between adjacent blades. The ends of the clappers on each blade form abutments for the ends of the clappers on the next adjacent blade and prevent excessive relative lateral movement of the blades.

In this embodiment the blades 5 are of composite construction and comprise a titanium pressure surface 7 terminating in titanium leading and trailing edges 8 and 9 respectively. The remaining portion 10 of the blade is made of a plastic material and the resulting blade is lightweight and suitable for inclusion in an engine which is to be used as a vertical lift engine having a thrust to weight ratio of at least 8.1 and preferably of 16.1 or more.

Each clapper 6 is of plastic material and is made in aer-ofoil shape to reduce the disturbances in the air flowing over the clappers. Each clapper is hollow and has a flange 11 at one. end for attachment to the blade. The crosssectional area of the hollow interior increases towards the flanged end of the clapper.

A pair of 'holes are drilled through the working sur faces of each blade and dowel pins 12 are fitted into the holes. Each dowel pin has a cylindrical central portion 13 and tapered end port-ions 14 and 15. The angle of the taper on the pins is substantially the same as the angle of taper of the internal cross section of the clapper. The dowel pins 12 are made a push fit into the holes in the blade but may also be cemented in.

The thickness of the titanium portion 7 may be arranged to increase locally in the area surrounding the holes to maintain the strength of the blades.

To assemble the clappers and the blade the clappers are merely fitted over the pins 12 and bonded thereon. A bond may also be formed between the clappers and the working surfaces of the blade at the flange 11. The bond may be achieved by resin bond or by a suitable adhesive.

Such an assembly of blades and clappers is shown in FIGURE 4.

In order to reduce still further the relative movement between two adjacent blades the abutting ends 16 of a pair of adjacent clappers may be bonded together or, as shown in FIGURE 5, a bonding strap 17 may be wound over the abutting ends. In this case a packing piece 18 is inserted between the two abutting faces 16 to prevent rubbing of the faces. The packing piece 18 also provides for ease of disassembly in that the packing piece can be sawn out from the joint without detriment to the clappers themselves and cheaply replaced.

The bonding strap 17 is wound around the clapper surfaces, over the abutting ends 16 of the clappers and the packing piece 18, and may then be heat cured or subjected to pressure to form a firm joint, depending on the material from which it is made. It will be appreciated that the bonding strap or connecting member 17 is strong in sheer but peelable so that when it is necessary to change a blade, the bonding strap or connecting member may be peeled off of the adjacent clapper members.

The material used for the strap may be a composite fiber reinforced plastic or resin.

The bonding strap 17 is only used to join the blades in pairs since it is undesirable to have all the clappers so joined.

FIGURE 6 illustrates a further embodiment of the invention wherein the clappers 6 have been moulded onto the blade in one operation. In this case the clappers 6 are made as solid members.

Although the invention has been described in this specific example herein two dowel pins are used to facilitate attachment of the clappers, the number of dowel pins used will depend upon the stream requirements of the blades. For instance a first stage compressor blade being lightly stressed may need only one dowel pin or perhaps no dowel pin at all, the assembly depending only on the strength of the bond between the flange 11 and the blade surfaces 7 and 10.

The invention is not intended to be limited to compressor blades or composite blade structures since the invention may be used to provide clappers on turbine blades or highly stressed compressor blades where metal blades and metal clappers may be used.

Again, the composite blades have been described as having a titanium pressure surface and titanium leading and trailing edges. The titanium portion may, however, be in the form of a spine down the middle of the blade and the plastic may be inserted in recesses in the titanium to provide the working surfaces.

The above method of making clappered blades can also be of use in the case where an engine which has run successfully using blades without clappers is modified and subsequently found to require clappered blades. It is necessary only to design clappers which can be fitted to the existing blades which may then be re-used.

We claim:

1. A rotor for a compressor or turbine of a gas turbine engine comprising: a rotor disc member; a plurality of blades mounted on the periphery of said rotor disc member, each of said blades having aerofoil shaped surfaces; at least one clapper member projecting from the aerofoil surface of each of said blades, each clapper member projecting towards the clapper member of the next adjacent blade; and a sleeve-like connecting member fitting over adjacent ends of adjacent clapper members of two adjacent blades in at least each alternate space between the blades to secure the ends of said adjacent clapper members together, said connecting member being made from 4 a strip of material strong in sheer and readily peelable whereby said connecting member may be peeled off of said adjacent clapper members when it is necessary to remove a blade from said disc member.

2. A rotor as claimed in claim 1 in which said sleevelike connecting member is made of a plastic material.

3. A rotor as claimed in claim 2 in which said plastic material is fiber reinforced.

4. A rotor as claimed in claim 2 including a backing piece inserted between the adjacent ends of the clapper members of adjacent blades and within said sleeve-like connecting member.

5. A rotor as claimed in claim 1 and in which the clapper members are of aerofoil shape.

6. A rotor as claimed in claim 1 and in which both the blades and the clappers are made of a plastic material.

7. A rotor as claimed in claim 1 and in which the blade is composed of both metal and plastic portions and the clapper members are made of a plastic material.

8. A rotor as claimed in claim 1 and in which means are provided for attaching each clapper member separately to a blade.

9. A rotor as claimed in claim 8 and in which the said means comprises a plurality of pins projecting from the aerofoil surfaces of the blade.

10. A rotor as claimed in claim 9 and in which the clapper members are bonded onto the pins.

References Cited UNITED STATES PATENTS 1,618,296 2/1927 Ray 253-77 1,749,449 3/1930 Stevens 253-77 2,771,267 ll/ 1956 Weymouth 25377 2,912,157 11/1959 Taylor 25377 X FOREIGN PATENTS 358,406 10/ 1931 Great Britain.

MARTIN P. SCHWADRON, Primary Examiner.

EVERETTE A. POWELL, JR., Examiner. 

1. A ROTOR FOR A COMPRESSOR OR TURBINE OF A GAS TURBINE ENGINE COMPRISING: A ROTOR DISC MEMBER; A PLURALITY OF BLADES MOUNTED ON THE PERIPHERY OF SAID ROTOR DISC MEMBER, EACH OF SAID BLADES HAVING AEROFOIL SHAPED SURFACES; AT LEAST ONE CLAPPER MEMBER PROJECTING FROM THE AEROFOIL SURFACE OF EACH OF SAID BLADES, EACH CLAPPER MEMBER PROJECTING TOWARDS THE CLAPPER MEMBER OF THE NEXT ADJACENT BLADE; AND A SLEEVE-LIKE CONNECTING MEMBER FITTING OVER ADJACENT ENDS OF ADJACENT CLAPPER MEMBERS OF TWO ADJACENT BLADES IN AT LEAST EACH ALTERNATE SPACE BETWEEN THE BLADES TO SECURE THE ENDS OF SAID ADJACENT CLAPPER MEMBERS TOGETHER, SAID CONNECTING MEMBER BEING MADE FROM A STRIP OF MATERIAL STRONG IN SHEER AND READILY PEELABLE WHEREBY SAID CONNECTING MEMBER MAY BE PEELED OFF OF SAID ADJACENT CLAPPER MEMBERS WHEN IT IS NECESSARY TO REMOVE A BLADE FROM SAID DISC MEMBER. 